When you’re doing cardio, it’s pretty easy to track how many calories you’re burning because your heart rate stays up the whole time. But with strength training, it gets a bit trickier since you have those work and rest periods between sets.
When you’re lifting weights, your heart rate goes up, and then it drops during your rest breaks. Even so, you’re still burning more calories than you would if you were just chilling out, thanks to something called oxygen debt—basically, your body uses extra oxygen after a tough workout.
Plus, you keep burning calories even after you leave the gym until your body calms down. This makes it hard to get an exact number on how many calories you’ve burned. The most accurate way to measure it is with a gas analyzer—a special mask you wear during your workout that tracks your oxygen use and calculates calories burned.
But don’t worry! We can still get a rough idea of how many calories strength training uses based on some research.
How Many Calories Does Strength Training Burn?
In one study, researchers looked at how many calories guys and gals burned during strength training. Participants did eight different exercises, each with one set of 15 reps, using weights that were just right for them to hit that number.
The results showed that men burned about 5.6 calories per minute, while women burned around 3.4 calories per minute. This makes sense since the average weight for women in the study was 62 kg, while men averaged 90 kg, and men generally have more muscle mass.
In another experiment, women burned about 155 calories during a full workout of 10 exercises, each done in three sets of 10 reps with a minute of rest in between. They also burned an extra 31 calories during recovery because of that oxygen debt. The whole workout took 45 minutes, so they were burning about 3.4 calories per minute again. The average age of the women was 29, and they weighed around 59 kg.
So, to sum it up, women burn about 3.4 calories per minute during strength training, while men burn about 5–6 calories per minute.
It doesn’t really matter if you’re lifting heavy weights for fewer reps or lighter weights for more reps—what counts is pushing your muscles until they’re pretty tired.
In another study, researchers wanted to see how much energy different intensity levels of strength training used. Young, fit guys did classic strength exercises like bench presses and squats, and the researchers used a gas analyzer to track their calorie burn.
They tested three different training styles:
- Low intensity: 2 sets of 15 reps at 60% of their max weight.
- Medium intensity: 3 sets of 10 reps at 75% of their max weight.
- High intensity: 6 sets of 5 reps at 90% of their max weight.
In all cases, the guys took 2-minute breaks between sets.
The results showed that high-intensity training burned about 610 calories, medium intensity burned 360 calories, and low intensity burned 283 calories. But the difference was mainly because of how long each session lasted—low intensity took 44 minutes, medium took 61 minutes, and high intensity took 116 minutes.
So, during low-intensity strength training, the guys burned about 6.4 calories per minute, medium intensity burned 5.9 calories per minute, and high intensity burned 5.2 calories per minute. It turns out that doing more reps with lighter weights can actually burn more energy than fewer reps with heavier weights. But if everyone trained for the same amount of time, the difference in calories burned would only be about 50 calories.
On the flip side, the researchers didn’t measure oxygen debt in this study. There’s some evidence that after heavy lifting, people burn more calories at rest compared to after moderate workouts, but this hasn’t been fully explored yet.
How to Estimate Calories Burned During Strength Training
You can get a rough idea of how many calories you burned by multiplying your workout time by the average energy expenditure—3.4 calories per minute for women and 5.6 calories per minute for men.
Keep in mind that these numbers come from studies involving young people with low body fat. If you have a different body composition, you might burn fewer calories.
Your calorie burn during training can also change based on a few factors:
- Rest time between sets: In studies, people rested for 60-120 seconds. If you spend a lot of time chatting or scrolling through your phone, you might burn fewer calories. On the flip side, cutting down your rest time can boost your calorie burn.
- Body composition: Muscle burns more energy than fat, so the more muscle you have, the more calories you’ll burn both at rest and during workouts.
- Fitness level: The longer you do an activity, the fewer calories you burn. When you first start, your body works harder, but over time, it gets more efficient, and you burn less energy.
It’s tough to predict exactly how many calories you’ll burn if you change your rest time or have a different body composition. Just keep in mind that these numbers are general estimates, and your actual calorie burn might be a bit higher or lower.
